1. Technical Field
This application relates to semiconductor memory and, in particular, to trim settings.
2. Related Art
A trim set may include one or more trim settings, such as a program voltage, a step-up voltage, and/or a program pulse width. Each trim set may be associated with a corresponding portion of semiconductor memory. Each portion of memory may be a page, a block, a column, or any other suitable division of the semiconductor memory. When the portion of the memory is programmed as part of a write operation, the trim settings, such as the program voltage, of the corresponding trim set may be used to program the portion of the semiconductor memory.
The trim settings may include one or more parameters related to read operations. For example, the trim settings may include a sensing time or sense amplifier delay, and/or a sensing or sense reference voltage. The parameters related to read operations may be used to read data from the associated portion of the semiconductor memory.
In some examples, one or more of the parameters of a trim set may vary over time. For example, voltage and/or charge settings, such as the program voltage and the sense reference voltage may increase over time. The change in trim settings over time may be referred to as trim advancement.
When a first trim set is replaced with a second trim set as part of a trim advancement, every read of the portion of memory associated with the first trim set may result in shifted read or dynamic read. The shifted read or dynamic read may be performed with the settings of the first trim set instead of the second trim set because the portion was programmed with the first trim not the current second trim set. A shifted read or dynamic read may slow down performance of the semiconductor memory. In some examples, trim advancement may impact the data retention margin, so the portions of memory written with the first trim set may start getting errors, thereby slowing down the read.
Data written with the first trim set to a first portion of the memory may be copied to a second portion of the memory, where the data is programmed with the second trim set. However, such copying may increase write amplification, which may decrease the endurance of the memory.